Temporal characteristics in the fluent speech of child stutterers and nonstutterers

Past research reveals that adult stutterers often possess aberrant speech-timing abilities. As yet, only Healey and Adams (1981) have investigated these abilities in child stutterers. The present study attempted to assess the speech-timing skills of child stutterers and normal-speaking children while performing both simple and complex speech. Each subject was required to participate in two tasks: a sentence repetition task for simple speech and a story-retelling task for complex speech. Results supported those found by Healey and Adams, indicating that child stutterers have speech-timing abilities similar to normal-speaking children in simple speech tasks. The complex task, however, revealed that stutterers exhibited more frequent and longer interword pauses than nonstutterers. Two hypotheses generated from past research are offered to explain these differences. A third untested theory is also presented.     

Perceptual comparisons of adolescent stutterers' and nonstutterers' fluent speech

Numerous investigators have reported that listeners are able to perceptually differentiate adult stutterers' and nonstutterers' fluent speech productions. However, findings from similar studies with children ranging in age from 3 to 9 yr have indicated that perceptual discrimination of child stutterers is difficult. A logical extension of this line of investigation would be to determine when during maturation from childhood to adulthood stutterers' fluent speech becomes perceptibly different than nonstutterers'. Therefore, in this study similar fluent speech samples from seven 12–16-yr-old adolescent male stutterers and seven matched nonstutterers were analyzed perceptually in a paired stimulus paradigm by 15 sophisticated listeners. Individual subject analyses using signal detection theory revealed that five of the seven stutterers were discriminated. When averaged for subject group comparison, these findings indicated that listeners successfully discriminated between the fluent speech of the two groups. Therefore, the perceptual difference in fluent speech production reported previously for adults appears to be present by adolescence.     

Unsophisticated judges' perceptual evaluations of the speech of “successfully treated” stutterers

The purpose of this investigation was to determine if the speech of “successfully therapeutized” stutterers and a group of partially treated stutterers was perceptually different from the speech of normal speakers when judged by unsophisticated listeners. Tape-recorded speech samples of treated stutterers were obtained from leading proponents of (1) Van Riperian, (2) metronome-conditioned speech retraining, (3) delayed auditory feedback, (4) operant conditioning, (5) precision fluency shaping, and (6) “holistic” therapy programs. Fluent speech samples from these groups of stutterers were paired with matched fluent samples of normal talkers and presented to a group of 20 unsophisticated judges. The judges were instructed to select from each paired speech sample presented to them the one produced by the stuttering subject. The results of the analyses showed that five of seven experimental groups were identified at levels significantly above chance. It can be concluded that the fluent speech of the partially and successfully treated stutterers was perceptibly different from the utterances of the normal speakers and that the perceptual disparity can be detected, even by unsophisticated listeners.     

The voice problems of stutterers: A practical approach from clinical experience

Voice disorders, which may be caused by the stuttering problem, have been noted in at least one-third of stutterers seen. Basically, stutterers have false speech images that normal speech is perfect and without natural dysfluencies (repetitions, pauses, etc.). Many stutterers also have erroneous vocal images of how they should or should not sound. Both images control speech and voice. Clinical experience indicates that vocal rehabilitation should be used in conjunction with speech therapy for many stutterers.     

Attention and stuttering: Do stutterers think too much about speech?

In this investigation the ability of stutterers and nonstutterers to simultaneously perform speech and nonspeech tasks was compared. Subjects were 10 stutterers and 10 nonstutterers. Two experiments were conducted. In the first, subjects performed a non-attention-demanding gross-motor task while they read aloud. In the second, subjects performed an attention-demanding task (reading comprehension) during speech. Results indicated that there was no significant change in the disfluency values of stutterers during the motor activity or as a result of the reading comprehension task. However, stutterers were found to perform significantly poorer than nonstutterers on the reading comprehension task. This finding was taken as evidence that stutterers devote more attention to speech than do nonstutterers.     

Perceptual study of the speech of “successfully therapeutized” stutterers

The purpose of this investigation was to determine if the fluent speech of “successfully therapeutized” stutterers and a group of partially treated stutterers was perceptually different from the fluent speech of normal speaking subjects. Tape recorded speech samples of treated stutterers were obtained from leading exponents of (1) Van Riperian, (2) metronome-conditioned speech retraining, (3) delayed auditory feedback, (4) operant conditioning, (5) precision fluency shaping, and (6) “holistic” therapy programs. All forms of disfluency were edited out of these tapes. The remaining samples were then paired with matched fluent samples of normal talkers and presented to a group of 20 sophisticated judges. The judges were instructed to select from each paired speech sample presented to them the one produced by the stuttering subject. The results of the analyses of variance for correct identification of the stutterers showed that the partially treated stutterers, as well as each group of therapeutized stutterers, were identified at levels significantly above chance. This meant that the fluent speech of the partially and successfully treated stutterers was perceptibly different from the utterances of the normal speakers sampled. In addition, the analyses of variance also revealed that all stuttering groups had a significant severity factor. This finding indicated there was a significant difference between the severity subgroup in all the samples investigated. These results were discussed in terms of their clinical implications.     

The speech production abilities of stutterers: Recent, ongoing, and future research

Recent and ongoing research into the speech production abilities of stutterers has followed four disparate paths. First, there have been objective studies of physiologic, aerodynamic, and acoustic parameters of stutterers' habitual speech patterns and the patterns they display while speaking in the presence of such novel stimuli as DAF or masking. Second, investigators have undertaken the fiberoptic examination of stutterers' larynges during fluent and stuttered utterances. Third, there have been studies of the speed with which stutterers start and terminate voicing independent of the act of speaking. Finally, there have been investigations of possible perceptible differences between the fluency of stutterers and normal speakers. Each of these four types of research is examined. Tentative conclusions are drawn, and directions for future theorizing and experimentation are suggested.     

Word fragmentations and repetitions in the spontaneous speech of 2–6-yr-old children

Samples of spontaneous speech of 110 nursery school children, aged 2 yr, 1 mo to 6 yr, were written down. Two of the children were regarded as stutterers by the parents and the nursery school personnel. Instances of word and phrase repetitions and word fragmentations were marked. Fragmentation of a word before the whole word is pronounced was used as criterion of stuttering. The nonstutterers had an average frequency of word repetitions of 6.3%, while word fragmentations were virtually nonoccurrent. The frequency of word repetitions decreased with increasing age. Relating word repetitions to grammatical complexity of speech, it was found that the decrease was particularly large at a certain point of the grammatical development. The two stutterers had, in addition to normal frequencies of word repetitions, marked occurences of word fragmentations (2.8 and 4.1%).     

Adaptation effect in nonfluent speech behavior of controlled stutterers and nonstutterers

The adaptation effect in stuttering behavior has received considerable attention. Adaptation effect is defined as the reduction in the frequency of nonfluencies in the speech of subjects during successive readings of the same passage. The objective of this investigation was to assess the adaptation effect of nonfluent speech behavior of controlled stutterers and nonstutterers. The subjects included 35 controlled stutterers and 35 nonstutterers matched for factors of sex, grade level, and age. Results suggest a significant mean difference between the number of nonfluencies between trials of controlled stutterers with evidence of adaptation in the speech of nonstutterers. Nonstutterers demonstrate significant mean differences in nonfluencies among replicated testing occasions. Findings of this investigation suggest that both controlled stutterers and nonstutterers demonstrate similar adaptation regarding their nonfluent speech behavior. Issues and import for future research are offered.     

Speech and bimanual hand organization in adult stutterers and nonstutterers

A multivariate approach was used to investigate the relationship between speech fluency and bimanual handwriting in right-handed male stutterers and nonstutterers. Handedness was determined by the Harris Test of Lateral Dominance. Subjects were required to write the numbers 1 through 12 simultaneously, as quickly as possible. Speech measures were derived from the Stuttering Severity Instrument and from a reading passage. Stutterers performed more poorly than nonstutterers on all speech measures. There were no differences in bimanual handwriting performance for the dominant hand. However, stutterers performed more poorly than nonstutterers in nondominant handwriting. There were no relationships between speech measures and bimanual handwriting for stutterers or nonstutterers. Some stutterers performed better on the handwriting task than did some nonstutterers. It is suggested that disorganization in interhemispheric integration functions may be a more fundamental problem in stuttering than is incomplete cerebral dominance.     

Perceptual evaluation of the speech before and after fluency shaping stuttering therapy

An often-cited criterion for assessing the effect of a stuttering therapy is the ability of the stutterers to produce normally fluent speech. Many modern stuttering therapies use special techniques that may produce stutter-free speech that does not sound completely normal. The present study investigates this problem in the framework of the Dutch adaptation of the Precision Fluency Shaping Program.

Pre-, post-, and -year follow-up therapy speech samples of 32 severe stutterers who were treated in a four-week intensive therapy are compared with comparable samples of 20 nonstutterers. For that aim the samples were rated on 14 bipolar scales by groups of about 20 listeners. The results show that the speech of the stutterers in all three conditions differs significantly from the speech of the nonstutterers. The pretherapy speech takes an extreme position on a Distorted Speech dimension, due to the large proportion of disfluencies. The posttherapy speech has extremely low scores on a Dynamics/Prosody dimension, a‘1 while the follow-up therapy speech differs from the normal speech on both dimensions, but now the distances are smaller. These results are discussed in relation to the severity of the stuttering problem in the group of treated stutterers. Finally, implications for future research on therapy evaluation are discussed.     

The mean fundamental frequency in stutterers and nonstutterers during reading and spontaneous speech

Corresponding to the higher tension of muscles involved in speech production, a higher mean fundamental frequency should be expected in stutterers as compared to nonstutterers. It could be shown by the change scores of the mean fundamental frequency from reading to free conversation that stutterers tend to have a higher fundamental frequency during spontaneous speech.     

Dichotic ear preferences of stuttering children and adults.

39 stutterers and 39 normal speakers indicated their ear preferences for dichotically presented words and digits. A single response mode for both dichotic words and digits was selected to study speech perception. Stutterers showed significantly less of the normal right-ear preference for dichotic words and digits than non-stutterers. The proportion of stutterers who failed to demonstrate a right-ear preference for dichotic words was significantly greater than for non-stutterers. 18% of the stutterers and none of the non-stutterers showed reversed or a left-ear preference for dichotic digits. Although non-stuttering children and adults performed alike on the dichotic tasks, the right-ear dichotic-words scores of stuttering children were significantly smaller than those of adult stutterers. The results are related to an early notion that stuttering may be related to mixed dominance and recent evidence showing that large percentages of older stuttering children show spontaneous remission of stuttering.     

Speech errors, disfluencies, and self-repairs of stutterers in two accuracy conditions

The purpose of the present study was to see whether the covert repair hypothesis, which views normal disfluencies as the by-products of covert self-repairing of internal speech (programming) errors, applies to habitual stutterers. To this end, we examined the effects of emphasis on speech accuracy in stutterers on three sorts of incidents: speech errors, disfluencies (also including stuttering), and self-repairs. In a condition in which they performed a speech task under instructions stressing the accuracy of speaking, stutterers made considerably fewer speech errors, than in a condition in which speech accuracy could be ignored. On the other hand, disfluency and self-repair rates remained about the same. They did increase, however, relative to speech error rates with accuracy emphasis. A control group of normal speakers performed in a similar way. Apparently, disfluencies behaved like self-repairs. These results support the covert repair hypothesis of disfluency, both for stutterers and for normal speakers.     

Vocal changes in stutterers and nonstutterers during monotoned speech

For years, reports have circulated that stutterers experience marked decrements in their stuttering when they speak or read in monotone. Wingate has suggested that the ameliorative effects of various novel speaking conditions on stuttering can be attributed to modifications in vocalization induced by such conditions. The present study was conducted to see whether this explanation would extend to monotoned speech as well. Ten teenage and adult stutterers and 10 normal speakers were tested in control and monotone reading conditions. Dependent measures were the frequencies of disfluency and stuttering, fundamental frequency, fundamental frequency standard deviation, vocal SPL, vocal SPL standard deviation, and fluent reading rate. Only within-group statistical comparisons were made, because members of the two groups could not be matched pairwise along critical vocal parameters. The major findings of this study indicated that across the two conditions, both groups significantly reduced their fundamental frequency, fundamental frequency standard deviation, vocal SPL and vocal SPL standard deviation. Only the stutterers exhibited a significant decrement in disfluency and stuttering. The normals did not evince enough disfluency in the control condition for a reduction to occur during monotoning. Neither group effected a reduction in fluent reading rates. These and other findings and interpretations are discussed relative to Wingate's modified vocalization hypothesis.     

Stuttering and anxiety: The difference between stutterers and nonstutterers in verbal apprehension and physiologic arousal during the anticipation of speech and non-speech tasks

To test if stressful anticipation of speech situations is a factor in eliciting stuttering behavior, the difference between 24 stutterers and 24 nonstutterers in verbal apprehension and physiologic activity was studied before and during speech tasks (reading and conversation), and nonspeech tasks (motor and intelligence task).Results indicate that the difference between stutterers and nonstutterers mainly were restricted to anxiety ratings assessed after each task. Heart rate, vasomotor responses, and electrodermal activity recorded before and during speech tasks were higher compared with the physiologic activity before and during nonspeech tasks but, unexpectedly, this was also the case for nonstutterers. It is concluded that stuttering is not elicited by anxiety.     

Dichotic speech perception: A comparison between stuttering and nonstuttering children

A stop consonant-vowel dichotic listening task was administered to 90 right- handed boys, 30 in each age group of 5, 7, and 9 yr. Half in each group were stutterers, half nonstutterers. Two and a half times as many stutterers as nonstutterers were found to display either a left-ear advantage (LEA) or no ear advantage (NEA). This finding suggested a greater tendency on the part of stutterers, as opposed to nonstutterers, for reversed or bilateral representation of the auditory speech areas of the brain. In addition, both stutterers and nonstutterers displayed significant developmental increases in the number of times they were able to identify both dichotic speech stimuli, thereby supporting the hypothesis of an age-related increase in children's total information processing capacity. The results are discussed in terms of the differences between stutterers and nonstutterers with respect to the issues of motor representation, cognitive modes, and higher-order linguistic processes.     

Effects of subgrouping in stuttering research

The most frequently utilized research design in stuttering research compares stutterers to nonstutterers, with the assumption that stutterers represent a homogeneous group. The present study examines the effects of subgrouping stuttering subjects. Sample populations were randomly selected from a pool of stuttering children, successively increasing the stringency of selection criteria for group membership. The groups were contrasted across five dependent variables. The results indicated that the performance differences between the groups increased as the selection criteria became more stringent. The findings were interpreted as supporting the need to more closely examine the individual differences of stutterers, deviating from the traditional research paradigm.     

Traits attributed to stuttering and nonstuttering children by their mothers

Traits attributed to 34 stuttering and 34 nonstuttering male children by their mothers using an adjective checklist were studied. Mothers of school-aged male stutterers were found to perceive their children as being more insecure, sensitive, anxious, withdrawn, fearful, and introverted than did mothers of nonstutterers. It was concluded that although research has not demonstrated a characteristic stuttering personality, stutterers continue to be perceived as having characteristic personality patterns.